1. Field of the Invention
The present invention relates to a means for compensating for null offsets in laminar flow jet deflection sensors and fluidic amplifiers.
2. Description of Prior Art
The null balance of jet deflection sensors and amplifiers has been a critical problem since the use of laminar flow devices. Null changes in these sensors and amplifiers are often due to power supply noise. When turbulent flow was utilized in these amplifiers, these effects of null offset were obscured by the large turbulent fluctuations. However, since laminar flow fields are essentially noise-free, these null offset effects are apparent. Jet flows within the fluidic amplifier should be such that equal output pressures are obtained in both output ports when there is no difference in pressure at the control ports. However, due to various nonlinearities in the device itself, a difference in output pressure is often seen even though there is no difference in pressure at the input or control ports. This difference in output in the absence of a difference in pressure at the input is called null offset. This null offset varies as the supply flow varies. Jet offset at the splitter has been found to be the dominant cause of this null offset problem.
In order to overcome this problem of null offset, several fabrication techniques have been attempted with some success. Nevertheless, there exists a need to more accurately null balance a given element by a trim circuit coupled to the basic mechanical device. The purpose of this disclosure is to describe a trim circuit that allows adjustment of the null, and the change in null offset, with supply changes in laminar flow devices.